Poly(neopentylene carbonate) Hyperstars

Summary: Branched aliphatic polycarbonates were synthesized by ring opening polymerization of 5,5-dimethyl-1,3-dioxane-2-one (NPC) initiated from polyfunctional alcohols and a commercial hyperbranched polyester (BOLTORN®). Polymerizations in the presence of fumaric acid under bulk conditions allowed high conversion (80%) without gelation. The synthesis of polymers with long chain branches was confirmed by size exclusion chromatography and universal calibration. The Mark–Houwink exponent decreased, indicating an increased density, while increasing the number of arms. The star polymers with up to four arms showed thermal properties Tg (20–30 °C) and Tm (100–110 °C) similar to linear PNPC. Boltorn™ hyperbranched polymer with radial polycarbonate grafts.